Use custom dependency resolution

- Use Apache Ivy to resolve artifact URLs
- Update build model with full artifact IDs
- Generate Maven module metadata to support dynamic version constraints
- Resolve snapshot versions and generate snapshot metadata
- Add test fixtures and rewrite Gradle plugin tests
- Update dependencies

fixtures/subprojects/multi-module/groovy/child-b/build.gradle

@@ -0,0 +1,8 @@
+plugins {
+    id 'java'
+}
+
+dependencies {
+    implementation project(':child-a')
+    implementation 'com.squareup.moshi:moshi:1.8.0'
+}